Question

fie progresia aritmetica in care a1=6 si a2=5 . Calculati a7 .

Answer 1

$\displaystyle a_1=6 \\ a_2=5 \\ a_7=? \\ r=a_2-a_1=5-6=-1 \\ a_7=a_{7-1}+r=a_6+r=a_1+6r=6+6 \cdot (-1)=6-6=0$